US4032296A - Electrolytic conductivity detector system - Google Patents

Electrolytic conductivity detector system Download PDF

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US4032296A
US4032296A US05/648,517 US64851776A US4032296A US 4032296 A US4032296 A US 4032296A US 64851776 A US64851776 A US 64851776A US 4032296 A US4032296 A US 4032296A
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conductivity
detector
gas
solvent
liquid
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Randall C. Hall
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Purdue Research Foundation
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • G01N30/02—Column chromatography
    • G01N30/62—Detectors specially adapted therefor
    • G01N30/64—Electrical detectors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/06—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a liquid
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • G01N30/02—Column chromatography
    • G01N30/84—Preparation of the fraction to be distributed
    • G01N2030/8405—Preparation of the fraction to be distributed using pyrolysis
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T436/00—Chemistry: analytical and immunological testing
    • Y10T436/15—Inorganic acid or base [e.g., hcl, sulfuric acid, etc. ]
    • Y10T436/153333—Halogen containing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T436/00—Chemistry: analytical and immunological testing
    • Y10T436/17—Nitrogen containing
    • Y10T436/173845—Amine and quaternary ammonium
    • Y10T436/175383—Ammonia
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T436/00—Chemistry: analytical and immunological testing
    • Y10T436/18—Sulfur containing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T436/00—Chemistry: analytical and immunological testing
    • Y10T436/20—Oxygen containing
    • Y10T436/204998—Inorganic carbon compounds

Definitions

  • This invention relates to an electrolytic conductivity detector system and more particularly to an electrolytic conductivity detector system for gas chromatography.
  • a detection system similar to that mentioned immediately hereinabove has also been used by D. M. Coulson, as reported in the Journal of Gas Chromatography, Volume 3, page 134, 1965, for the selective detection of halogen, nitrogen, and sulfur containing compounds.
  • the detector designed by Coulson unlike the Piringer and Pascalau detector, was designed to give a low response to carbon containing compounds, and the sensitivity achieved was approximately 1- 5 ng for polyhalogenated pesticides.
  • An electrolytic conductivity detector for the determination of chlorine, nitrogen, and sulfur compounds has also been recently described by P. Jones and G. Nickless in the Journal of Chromatography, Volume 73, page 19, 1972.
  • the detector described by Jones and Nickless includes components similar to that of the detector described by Coulson, but utilizes a commercially available conductivity cell and conductivity meter that was originally designed for monitoring liquid or ion-exchange chromatography columns to achieve the conductivity measurements.
  • the detector utilized was unlike that of the Coulson detector in that it employed a specially prepared nickel catalyst for the reduction of chlorine, nitrogen, and sulfur compounds to HCl, NH 3 , and H 2 S, respectively, and a dilute HCl solution was used as the conductivity solvent for monitoring Cl and N compounds.
  • Halogenated compounds were detected by an increase in conductivity, whereas nitrogen compounds were detected by a decrease in conductivity.
  • a dilute reactive EtOH--I.sub. 2 --HCl solution was used for the detection of sulfur containing compounds (H 2 S+ I 2 ⁇ S+ 2HI).
  • Sensitivity to the halogenated compounds was found to be approximately ten times that of the Coulson detector, but sensitivities to nitrogen and sulfur compounds were found to be similar to that of the Coulson detector.
  • electrolytic conductivity detectors have also been used heretofore, at moderate furnace temperatures, for the determination of certain compounds containing the same elements.
  • an electrolytic conductivity detector as designed by Coulson has been utilized heretofore for the selective determination of chlorinated hydrocarbon insecticides in the presence of polychlorinated biphenyls, the achieved selectivity being reported as >10 4 , with a furnace temperature of 710° C. and no reaction gas (See J. W. Dolan, R. C. Hall and T. M. Todd, J. Ass. Office, Anal. Chem., Vol. 55, page 537, 1972), and the same type detector has also been utilized with a furnace temperature of 400°-600° C. for the selective detection of N-nitrosamines in the presence of other nitrogen compounds (See J. W. Rhoades and D. E. Johnson, J. Chromtogr. Sci., Vol. 8, page 616, 1970).
  • This invention provides an electrolytic conductivity detector that is small and compact yet is rugged and is suitable for gas chromatography. Small molecules that will support conductivity are mixed in a gas-liquid contactor with a solvent after which liquid phase is separated with conductivity measurement of separated liquid phase then occurring. A unitized separator-conductivity cell is preferably utilized to provide separation and conductivity measurement. Enhanced sensitivity and versatility, as well as compactness and simplicity of design and construction, are provided.
  • FIG. 1 is a block diagram of the electrolytic conductivity detector system of this invention
  • FIG. 2 is an exploded side view of the unitized electrolytic conductivity detector including one embodiment of the unitized separator-conductivity cell;
  • FIG. 3 is a cutaway side view of the preferred embodiment of the unitized separator-conductivity cell of the electrolytic conductivity detector shown in block form in FIG. 1;
  • FIG. 4 is a side sectional view of the unitized separator-conductivity cell shown in FIG. 2;
  • FIG. 5 is a side sectional view of a preferred embodiment of the unitized separator-conductivity cell as shown in FIG. 3;
  • FIG. 6 is an alternate embodiment illustrating a separate separator and a separate conductivity cell in a side sectional view
  • FIG. 7 is a second alternate embodiment of a unitized separator-conductivity cell
  • FIG. 8 is a third alternate embodiment of a unitized separator-conductivity cell
  • FIG. 9 is a cutaway perspective view of a reaction furnace that may be utilized with this invention.
  • FIGS. 10A through C are graphs illustrating detector response to chlorinated hydrocarbon pesticides in the reductive mode
  • FIGS. 11A and B are graphs illustrating detection response to chlorinated hydrocarbon pesticides in the oxidative mode
  • FIG. 12 is a graph illustrating detector response (peak height) versus grams of heptachlor
  • FIGS. 13A and B are graphs illustrating comparison of microelectrolytic conductivity and flame photometric response to sulfur containing compounds.
  • FIGS. 14A, B, C and D are graphs illustrating detector response identifying the preferred embodiment of the separator-conductivity cell.
  • the system for the gas chromatograph electrolytic conductivity detector may include a furnace 25 (or other device for the formation of compounds that will support electrolytic conductivity), a gas-liquid contactor 26, a unitized gas-liquid separator-conductivity cell 27, a solvent delivery system 29, and electrical components 30 for measuring conductivity.
  • a compound is transferred from a supply source, such as from a gas chromatograph 32, for example, to the furnace where it is degraded to small inorganic compounds that will support electrolytic conductivity, such as, for example, HCl, SO 3 , NH 3 , or CO 2 .
  • gas from an appropriate reaction gas source 36 may be utilized to carry the compound to furnace 25, and the gas reaction source is preferably connected to furnace 25 through a conventional valve (not shown).
  • the small gaseous molecules are transported from furnace 25 to gas-liquid contactor 26, preferably through glass or Teflon capillary tubing. At gas-liquid contactor 26, the molecules are mixed either with an aqueous or organic solvent.
  • the gas and liquid phases are then conducted to gas-liquid separator-conductivity cell 27 where the liquid phase is separated from any insoluble gases with the collected liquid phase being then utilized for measurement of the electrolytic conductivity.
  • the unitized separator-conductivity cell functions by having the separator also serve as a concentric electrode conductivity cell.
  • the heterogenous gas-liquid mixture from the gas-liquid contactor separates into two smooth flowing homogeneous phases when the mixture comes into contact with the inside wall of the detector block of the separator-cell.
  • the liquid phase then flows down the wall as a sheath with the gas phase as the core.
  • the liquid phase passes between the inside wall of the detector block (outer electrode) and the outside wall of the inner gas exit tube (inner electrode) of the separator-cell, with the phases then being finally vented through the gas exit tube.
  • the driving forces that make the separator-cell function are the bonding attraction between the liquid phase and detector surface, the downward forces of the moving liquid phase, and the positive pressure on the liquid phase in the detector.
  • the principal force responsible for separation of the gas-liquid mixture is the bonding attraction between the liquid phase and the separator surfaces.
  • the gases are forced to separate from the liquid phase and formed into a gaseous core that is vented from the detector.
  • the stated remaining forces that make the separator-cell function namely the downward forces of the moving liquid phase and the positive pressure on the liquid phase of the detector cause the liquid phase to flow between the inner and outer electrodes.
  • the positive pressure on the liquid phase is due to the continuous flow of liquid and gas phases into the detector, while the bonding attraction is the result of the materials used.
  • the bonding attraction of the liquid phase to the separator surfaces is thought to be the result of known forces such as van der Walls and hydrogen bonding.
  • electrolytic conductivity detectors can be achieved by reaction gas composition, reaction temperature, use of abstractors, and conductivity solvent.
  • SO 2 -SO.sub. 3, HCl, CO 2 , H 2 O, and N 2 are the products produced from compounds containing sulfur, chlorine, or nitrogen. Water and N 2 give little or no response, SO 2 and SO 3 can be removed by a CaO scrubber in the furnace tube, HCl can be removed by a AgNO 3 scrubber, and the response due to CO 2 can be made negligible by a very short gas-liquid contact time or the use of a nonaqueous solvent.
  • measurement of conductivity at conductivity cell 27 can be made by a conventional conductivity meter 40 and the resulting readings at the meter can, if desired, be recorded by a recorder 41 connected conventionally with meter 40.
  • Solvent circulating system 29 includes a solvent reservoir 43 which receives the solvent passed through the conductivity cell.
  • the liquid is pumped from reservoir 43 by a means of a pump 44, which pump may, for example, be a Teel No. 1P676 centrifugal pump with the solvent from the reservoir being pumped through a bed of Duolite ARM-381 mixed H/OH ion exchange resin (not shown) to gas-liquid contactor 26.
  • a valve (not shown) can be utilized to regulate flow rate.
  • FIG. 2 An exploded view of a portion of the electrolytic conductivity detector system of this invention is shown in FIG. 2 with one embodiment of the separator-conductivity cell shown.
  • gas-liquid contactor 26 is mounted to detector cap 49 with gas-liquid separator-conductivity cell 27 being mounted below cap 49.
  • Conductivity cell electrical leads 50 and 51 extend upwardly therefrom through detector cap 49 and are connected with the conductivity meter 40.
  • a brass solvent splatter shield and inner electrode connector 52 is mounted on inner tube and electrode 53.
  • a stainless steel shield and solvent cup 54 fits over the separator-conductivity cell 27 and a reservoir cap 55 is positioned at the bottom of the detector.
  • Cap 55 has a tube 56 extending therefrom connected to inner tube 53 through which solvent is expelled from the detector.
  • the detector as shown in FIG. 2, is small and compact and need have a diameter no greater than about one inch.
  • FIG. 3 shows a side view of the preferred embodiment of the unitized electrolytic conductivity detector system.
  • the detector includes a contractor block 57, preferably of Teflon.
  • Block 57 has a bore therein for receiving a solvent delivery tube 58, the bore extending downwardly to the central portion of the block to communicate with a side bore opening to reaction product delivery tube 60.
  • the reaction product delivery bore is preferably of the same dimensions as the solvent delivery bore 58.
  • a solvent-gas delivery passageway 61 extends downwardly from the junction of the inlet bores, the delivery passageway opening into the upper end of the unitized separator-conductivity cell 63 (shown in greater detail in FIG. 5).
  • Solvent delivery passageway 61 is preferably of the same dimensions as the inlet bores.
  • the unitized separator-conductivity cell 63 has an insulating sleeve 64 extending to an inner electrode connecting block 65 adapted to receive a tube 66 at the lower end through which gas and solvent may be expelled.
  • outer electrode and detector block 68 has a bore 69 therein for receiving the gas and liquid mixture from contactor 26.
  • Inner electrode and solvent liquid exit tube 53 extends upwardly and partially into the bore 69.
  • a reservoir 70 is formed between the block 68 and the upper portion of tube 53 with solvent being expelled from the reservoir through aperture 72 in tube 53 near the bottom of the reservoir to allow solvent removal from the separator-conductivity cell 27.
  • Insulating sleeve 74 surrounds tube 53 below reservoir 70 and sleeve 74 preferably extends to the upper edge of connector block 52 through which tube 53 extends and is electrically connected therewith.
  • the liquid and gas mixture is received in bore 69 from contractor 26.
  • the liquid phase flows downwardly into reservoir 70 where the conductivity measurement is obtained by means of the inner and outer electrodes 53 and 68 (during flow of liquid phase between the electrodes) connected through leads 50 and 51 to conductivity meter 40.
  • the liquid phase is then expelled from the separator-conductivity cell through aperture 72 and tube 53.
  • the preferred embodiment (63 is identified in FIG. 3) of the unitized separator-conductivity cell is shown in detail in FIG. 5.
  • the preferred embodiment is like separator-conductivity cell 27 except for modified stainless steel connector blocks 76 and 77.
  • Block 77 preferably engages the lower end of insulating sleeve 74 at the upper edge and has a cylindrical flange 78 extending outwardly from the lower edge, which flange receives a tube or the like such as shown in FIG. 3.
  • Block 76 has a beveled upper edge so as to be received in the mating lower portion of contactor block 57 as shown in FIG. 3. Operation of the preferred embodiment is identical to that as described hereinabove with respect to the embodiment shown in FIGS. 2 and 4.
  • FIG. 6 A still further alternate embodiment for gas-liquid separator and conductivity measurement is shown in FIG. 6 to consist of a separator 80 and conductivity cell 81.
  • assembly block 83 has an axial bore therethrough, the upper end of which receives solvent-gas delivery tube 84 and may be, for example, a continuation of the solvent-gas delivery tube extending downwardly from gas-liquid contactor 26.
  • Assembly block 83 may be of stainless steel and the axial bore therein has a larger diameter in the lower portion thereof and has an upwardly extending gas exit tube 85 received therein. As shown, tube 85 extends to a point just below a tapered shoulder 86 forming the enlarged portion of the axial bore in the assembly block.
  • Gas exit tube 85 is of smaller diameter than the lower portion of the bore and is preferably 0.0625 inches outside diameter times 0.030 inches internal diameter with the spacing between the gas exit tube and the inner wall of the block 83 forming a small reservoir 87 therebetween (the internal diameter of the bore being preferably 0.0730 inches).
  • a solvent exit tube 88 preferably of Teflon having a 0.0625 inch outside diameter times 0.023 inch internal diameter, is received in a side bore in the assembly block and communicates with the reservoir 87 at or near the bottom thereof.
  • a seal 89 preferably of Teflon, is provided at the bottom of the reservoir extending between the inner wall of the assembly block and the outer wall of gas exit tube 85.
  • the gas and liquid phases enter vertically into the separator 80 through delivery tube 84 and flow down the outside walls and enter vertically into the small reservoir provided between the inner wall of the assembly block and the outer wall of gas exit tube 85.
  • the liquid phase collecting in the reservoir is then withdrawn therefrom through solvent exit tube 88 and conducted to conductivity cell 81.
  • Conductivity cell 81 is also shown in detail in FIG. 6.
  • a center electrode 91 preferably of 0.0625 inches outside diameter is received within the axial bore of an outer electrode 92 with center electrode 91 being maintained spaced from outer electrode 92 by means of Teflon seals 93 at each end of the cell.
  • a side bore in the outer electrode receives solvent entry tube 94, preferably having the same dimensions as solvent exit tube 88 (and connected thereto) of separator 80 and made also of Teflon. Tube 94 supplies liquid phase to passageway 95 in the conductivity cell formed between the center and outer electrodes.
  • a second side bore near the top of the conductivity cell receives solvent exit tube 96 for expelling liquid phase from the conductivity cell, the exit tube being preferably of Teflon and of 0.0625 inch outer diameter times 0.031 inches internal diameter.
  • a second alternate embodiment 99 of the unitized separator-conductivity cell is shown in FIG. 7 to include a stainless steel outer electrode and detector housing 100 with a central bore thereon.
  • a gas-liquid inlet and center electrode 101 extends downwardly into the central bore of housing 100 and terminates a short distance above a lower Teflon seal 102 at the bottom portion of the bore to form a passageway 103 between the inner and outer electrodes.
  • a gas exit tube 104 extends upwardly within the bore through lower seal 102 and extends partially within center electrode 101 so as to form a reservoir 105 therebetween.
  • An upper Teflon seal 106 seals the upper end of the passageway 103 formed between the inner and outer electrodes and a side opening exit tube 108 for solvent exit opens from the top of passageway 103 below seal 106.
  • embodiment 99 receives the liquid and gas mixture through inlet and center electrode 101.
  • the mixture separates in the tube 101 and a liquid phase is received in reservoir 105 and exits therefrom at the bottom of the reservoir through passageway 109 formed between center electrode 101 and lower seal 102.
  • the liquid phase exiting from the reservoir through passageway 109 is introduced into passageway 103 where it is urged upwardly between the inner and outer electrodes to exit from solvent exit tube 108, the conductivity measurement being made of the liquid phase while in passageway 109.
  • a third embodiment 112 of the unitized separator-conductivity cell is shown in FIG. 8 to include an outer electrode and detector housing 114 having a central bore therein, said bore being of reduced diameter at the top portion 115 to form a gas-liquid inlet.
  • An inner electrode and liquid exit tube 117 extends upwardly into the bore, said inner electrode 117 being maintained spaced from the outer electrode 114 by means of insulating sleeve 118.
  • Inner electrode 117 terminates before the reduced diameter portion 115 of the bore and a reservoir 119 is formed between the inner and outer electrodes.
  • a side-opening exit tube 120 opens from the bottom of the reservoir to allow liquid phase in said reservoir to exit from the separator-conductivity cell. Conductivity measurement is obtained from liquid phase in the reservoir while between the inner and outer electrodes.
  • the detector system of this invention features extremely small size as compared to heretofore known or utilized electrolytic conductivity detectors and may include a small furnace on the order of 2" ⁇ 2". This is contrasted, for example, to the detector of Coulson, referenced hereinabove, which utilizes an all glass detector assembly of about 4" ⁇ 26".
  • the detector also includes a gas-liquid separator that will function at any angle including being inverted, has separate 0 to m1 quantities of liquid, and is self-starting and maintaining.
  • the detector system also includes the use of an AC conductivity meter with synchronous detection that prevents peak broadening due to polarization effects and provides a linear dynamic range of at least 10 5 .
  • the detector system also allows the use of nonaqueous conductivity solvent (ETOH) which enables the detector to be operated in the oxidative mode without solvent venting and provides a selectivity >10 5 .
  • ETOH nonaqueous conductivity solvent
  • the overall design of the detector system of this invention enables the detector assembly to be mounted either at or removed from the furnace and the small size of the furnace allows it to be mounted in any location a standard gas chromatograph detector (i.e. flame ionization) can be mounted.
  • Furnace 25 is shown in detail in FIG. 9 for illustrative purposes.
  • furnace 25 includes a furnace housing 125, a quartz reaction tube 126, a reaction gas and column eluant gas entrance tee 127, and a tee mounting device 128.
  • a reaction tube securing device (not shown) can be utilized.
  • the furnace core includes an alumina tube 129 surrounding that portion 130 of quartz reaction tube 126 that is within the furnace with the alumina tube having No. 25 gauge Tophet 30 wire 131 wound thereabout. Insulating filler 132 then surrounds the alumina tube within the furnace.
  • the quartz reaction tube 126 is preferably mounted to the inlet tee by Teflon ferrules (not shown) and secured by a stainless steel nut 134.
  • Performance of the detector of this invention as shown in FIG. 8, is illustrated in the various graphs and charts of FIGS. 10 through 13.
  • the detector of FIG. 8 was evaluated both in the reductive and oxidative modes using a Chromatronix conductivity meter.
  • the detector furnace was operated at 820° centigrade in the reductive mode and at 840° centigrade in the oxidative mode with 1 cc/min of either hydrogen or oxygen reaction gas.
  • Reaction tubes were 6 mm OD ⁇ 0.5 mm ID ⁇ 150 mm length quartz tubes and were used empty with no prior conditioning.
  • the detector was mounted on a Tracor MT-220 gas chromatograph and interfaced to the column exit by approximately six inches of 1/16 inch stainless steel tubing.
  • Detector response to chlorinated hydrocarbon pesticides in the reductive mode for 1 ng (FIG. 10A), 0.1 ng (FIG. 10B), and 0.05 ng (FIG. 10C) of lindane, heptachlor, aldrin, heptachlor epoxide, and dieldrin, in order of elution, with a detector sensitivity of 0.2 ⁇ mho/mv.
  • Detector response for the same pesticides in the oxidative mode is shown for 1 ng with detector sensitivity of 0.4 ⁇ mho/mv (FIG. 11A) and 0.1 ng with detector sensitivity of 0.2 ⁇ mho/mv (FIG. 11B).
  • the detector of this invention exhibits high sensitivity and stability, the detector being much more sensitive than heretofore known detectors such as, for example, the Coulson electrolytic conductivity detector. Selectivity (relative to hydrocarbon) is also extremely high. Detector response (peak height) versus grams of heptachlor is shown in FIG. 12.
  • FIG. 13 A comparison of microelectrolytic conductivity and flame photometric responses to sulfur containing compounds is shown in FIG. 13.
  • the order of elution is diazinon, malathion, and parathion with FIG. 13A showing the electrolytic conductivity detector and FIG. 13B showing the flame photometric detector.
  • the electrolytic conductivity detector of this invention gives approximately 50% full scale deflection at 0.5% noise for 5 ng of diazinon, malathion, and parathion.
  • the flame photometric detector of the prior art gives only about 2% to 3% deflection at twice the noise level for the same quantity of compound.
  • the electrolytic conductivity detector of this invention has high sensitivity to sulfur compounds and has wide linear dynamic range (the flame photometric detector's response is exponential with concentration) making it an attractive device for the analysis of sulfur containing pesticides and air pollutants.
  • Detector response for the preferred embodiment shown in FIGS. 3 and 5 has been found to be at least as good as that shown for the detector in FIG. 8 as set forth hereinabove, and in many instances better.
  • the graphs of FIG. 14 illustrate performance of the detector utilizing the preferred embodiment of the separator-conductivity cell shown in FIGS. 3 and 5.
  • Detector response to chlorinated hydrocarbon pesticides in the reductive mode is shown, for illustrative purposes in FIG. 14.
  • a Tracor 550 as chromotograph was used, as were coiled glass columns with the same packing as described hereinabove in conjunction with the detector system producing the response indicated by the graphs as shown in FIGS. 10-13.
  • the column temperature was 185° centigrade and helium carrier gas was used at a flow rate of 30 ml/mi.
  • the furnace was operated at 850° centigrade with ⁇ /cc/min H 2 reaction gas.
  • the quartz tube utilized was 3 mm O.D. ⁇ 1 mm I.D. times 100 mm long, and solvent flow was 0.15 m1/min ETOH with a sensitivity of 0.2 ⁇ mho/mv.
  • Detector response is shown to chlorinated hydrocarbon pesticides in the reductive mode for 0.02 ng (FIG. 14A), 0.05 ng (FIG. 14B), 0.1 ng (FIG. 14C), and 0.2 ng (FIG. 14D) of lindane, heptachlor, aldrin, heptachlor epoxide, and dieldrin, in order of elution.
  • the electrolytic conductivity detector of this invention provides an improved detector having a separator and conductivity cell.
  • the gas-liquid separator-conductivity cell is felt to operate on a different principle than known prior detectors in that the geometry and principle of operation as utilized in the detector of this invention allows the dimensions to be easily altered as desired.
  • the ability of the detector of this invention to utilize small quantities of solvent is advantageous because the sensitivity of detecting devices such as conductivity cell is inversely proportional to the quantity of solvent utilized.
  • the electrolytic conductivity detector of this invention gives high performance, is easy to use, and is of small size and enables easy mounting.
  • the detector since the detector has high sensitivity, it is more useful than known devices of this type. Since the detector also has high selectivity and wide linear dynamic range, the detector is more useful in many instances than is the electron capture detector. Finally, the detector requires little maintenance and can be used trouble-free for long periods of time.
  • the gas-liquid separator-conductivity cell makes the detector capable of high performance and small size.
  • the concentric tube separator does not require a minimum solvent flow rate for operation, and since the primary force that drives the solvent through the conductivity cell is the downward force of the moving solvent, solvent flow rate through the cell approaches zero as the total solvent flow rate approaches zero.
  • the cell is always filled with solvent which prevents bubbles being lodged between the closely spaced electrodes, which is advantageous since the solvent often tends to channel around a bubble rather than displacing it.
  • the separator-conductivity cell functions efficiently and delivers a smooth solvent flow through the cell with solvent flow rates from 0.1 to 1.0 cc/min and gas flow rates from 5 to 500 cc/min or more.

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Cited By (16)

* Cited by examiner, † Cited by third party
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US4324573A (en) * 1979-10-24 1982-04-13 Eriksson Gunnar V Apparatus for removing oil from compressed air
EP0157160A1 (en) * 1984-03-02 1985-10-09 O.I. Corporation Electrolytic conductivity detector
US4656140A (en) * 1983-11-18 1987-04-07 Nakano Vinegar Co., Ltd. Method for a measurement of alcohol concentration in acetic acid fermenting broth
GB2210459A (en) * 1987-09-30 1989-06-07 Vaponics In-line concentric conductivity cell
US4917709A (en) * 1987-08-27 1990-04-17 O. I. Corporation Permeation pH control system
US5098563A (en) * 1988-06-09 1992-03-24 Chengdu University Of Science And Technology Low pressure ion chromatograph for the analysis of cations
US5194814A (en) * 1991-05-22 1993-03-16 Tremetrics, Inc. Electrolytic conductivity detector
US5665604A (en) * 1995-08-18 1997-09-09 The Regents Of The University Of California, Office Of Technology Transfer Method and apparatus for detecting halogenated hydrocarbons
US6425997B1 (en) 2000-06-20 2002-07-30 William C. Johnson Process for removal of chloride ions from steel surfaces
US20030164312A1 (en) * 1999-11-19 2003-09-04 Prohaska Otto J. Method and apparatus for enhanced detection of a specie using a gas chromatograph
US6682638B1 (en) 1999-11-19 2004-01-27 Perkin Elmer Llc Film type solid polymer ionomer sensor and sensor cell
US20050042148A1 (en) * 1999-11-19 2005-02-24 Prohaska Otto J. Method and apparatus for improved gas detection
US6929735B2 (en) 1999-11-19 2005-08-16 Perkin Elmer Instruments Llc Electrochemical sensor having improved response time
US7404882B2 (en) 1999-11-19 2008-07-29 Perkinelmer Las, Inc. Film-type solid polymer ionomer sensor and sensor cell
US20150276836A1 (en) * 2014-03-06 2015-10-01 The Board Of Regents Of The University Of Texas System Methods and devices for measuring conductivity of fluids
CN109142582A (zh) * 2018-09-21 2019-01-04 红河哈尼族彝族自治州农产品质量安全检验检测中心 气相色谱仪fpd检测器和ecd检测器共用的检测方法

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Cited By (29)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4324573A (en) * 1979-10-24 1982-04-13 Eriksson Gunnar V Apparatus for removing oil from compressed air
US4656140A (en) * 1983-11-18 1987-04-07 Nakano Vinegar Co., Ltd. Method for a measurement of alcohol concentration in acetic acid fermenting broth
EP0157160A1 (en) * 1984-03-02 1985-10-09 O.I. Corporation Electrolytic conductivity detector
US4555383A (en) * 1984-03-02 1985-11-26 O. I. Corporation Electrolytic conductivity detector
US4649124A (en) * 1984-03-02 1987-03-10 O. I. Corporation Electrolytic conductivity detection process
EP0307008A3 (en) * 1984-03-02 1989-05-10 O.I. Corporation Reactor for application to a gas chromatographic system
US4917709A (en) * 1987-08-27 1990-04-17 O. I. Corporation Permeation pH control system
GB2210459A (en) * 1987-09-30 1989-06-07 Vaponics In-line concentric conductivity cell
US5098563A (en) * 1988-06-09 1992-03-24 Chengdu University Of Science And Technology Low pressure ion chromatograph for the analysis of cations
US5194814A (en) * 1991-05-22 1993-03-16 Tremetrics, Inc. Electrolytic conductivity detector
US5665604A (en) * 1995-08-18 1997-09-09 The Regents Of The University Of California, Office Of Technology Transfer Method and apparatus for detecting halogenated hydrocarbons
US20050042148A1 (en) * 1999-11-19 2005-02-24 Prohaska Otto J. Method and apparatus for improved gas detection
US7404882B2 (en) 1999-11-19 2008-07-29 Perkinelmer Las, Inc. Film-type solid polymer ionomer sensor and sensor cell
US6682638B1 (en) 1999-11-19 2004-01-27 Perkin Elmer Llc Film type solid polymer ionomer sensor and sensor cell
US8123923B2 (en) 1999-11-19 2012-02-28 Perkinelmer Health Sciences, Inc. Film-type solid polymer ionomer sensor and sensor cell
US6929735B2 (en) 1999-11-19 2005-08-16 Perkin Elmer Instruments Llc Electrochemical sensor having improved response time
US20060000723A1 (en) * 1999-11-19 2006-01-05 Perkinelmer Las Electrochemical sensor having improved response time
US7013707B2 (en) 1999-11-19 2006-03-21 Perkinelmer Las, Inc Method and apparatus for enhanced detection of a specie using a gas chromatograph
US20060075802A1 (en) * 1999-11-19 2006-04-13 Perkinelmer, Las Method and apparatus for enhanced detection of a specie using a gas chromatograph
US7237430B2 (en) 1999-11-19 2007-07-03 Perkinelmer Las, Inc. Method and apparatus for enhanced detection of a specie using a gas chromatograph
US20030164312A1 (en) * 1999-11-19 2003-09-04 Prohaska Otto J. Method and apparatus for enhanced detection of a specie using a gas chromatograph
US7429362B2 (en) 1999-11-19 2008-09-30 Perkinelmer Las, Inc. Method and apparatus for improved gas detection
US20080264789A1 (en) * 1999-11-19 2008-10-30 Perkinelmer Las, Inc. Film-Type Solid Polymer Ionomer Sensor And Sensor Cell
US20080293158A1 (en) * 1999-11-19 2008-11-27 Perkinelmer Las, Inc. Method And Apparatus For Improved Gas Detection
US7736908B2 (en) 1999-11-19 2010-06-15 Perkinelmer Las, Inc. Method and apparatus for improved gas detection
US6425997B1 (en) 2000-06-20 2002-07-30 William C. Johnson Process for removal of chloride ions from steel surfaces
US20150276836A1 (en) * 2014-03-06 2015-10-01 The Board Of Regents Of The University Of Texas System Methods and devices for measuring conductivity of fluids
US9778299B2 (en) * 2014-03-06 2017-10-03 The Board Of Regents Of The University Of Texas System Methods and devices for measuring compositions of fluids
CN109142582A (zh) * 2018-09-21 2019-01-04 红河哈尼族彝族自治州农产品质量安全检验检测中心 气相色谱仪fpd检测器和ecd检测器共用的检测方法

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